New protein behind aging, cancer identified

Washington: Scientists have found a new aging-associated protein known to be involved in cancer.

The new study by investigators at Vanderbilt-Ingram Cancer Centre and the National Institutes of Health (NIH) identifies the protein SIRT2 as a tumour suppressor linked to gender-specific tumour development in mice.

Previous studies indicated that two other members of the sirtuin family – SIRT1 and SIRT3 – have tumour suppressor functions. These findings suggest that a third member of this protein family acts as a tumour suppressor.

“The single most important prognostic factor in cancer is increasing age,” said Gius, a professor of Radiation Oncology and associate professor of Cancer Biology at Vanderbilt-Ingram.

“It seems logical that the genes that play a role in aging – or perhaps better stated, anti-aging – would be connected to cancer,” he stated.

In the new study, Gius’ lab – working with senior author Chu-Xia Deng, Ph.D., and colleagues at the NIH’s National Institute of Diabetes and Digestive and Kidney Diseases – investigated the physiological functions of SIRT2 by eliminating the protein in cultured cells and in mice.

They found that SIRT2-deficient mice developed tumours in multiple tissues – and, strangely, male mice and female mice developed tumours in different tissues.

Lack of SIRT2 in female mice led to mammary (breast) tumours, while male mice lacking SIRT2 developed a range of gastrointestinal tumours (in the liver, pancreas, colon and stomach).

“It’s kind of a startling observation, that you’d knock a protein out, and you’d get gender-specific tumours, suggesting a physiological connection between gender and the function of sirtuin proteins,” Gius said.

While the mechanism underlying the gender-specific tumours was not determined, the researchers did find evidence that SIRT2 acted as a tumour suppressor in cultured cells.